In a small ramekin, whisk together the oyster sauce, soy sauce, fish sauce, and coconut sugar until the sugar is dissolved.
Heat the avocado oil in a large wok or stainless steel skillet over high heat until shimmering.
Add the garlic, chilies, and shallots to the pan. Sauté for 45 seconds until fragrant and slightly softened.
Add the ground beef to the skillet. Use a flat-edged spatula to break the meat into small crumbles. Sear until browned and no pink remains, approximately 5 to 7 minutes.
Pour the prepared sauce mixture over the beef. Toss continuously for 1 minute to ensure even glaze distribution and caramelization.
Remove the skillet from the heat source. Immediately add the fresh Thai basil leaves and lime juice. Fold the leaves into the beef until they are just wilted from the residual heat.
Distribute the beef mixture evenly among the 8 lettuce leaves. Serve immediately while the protein is hot and the lettuce is crisp.